Cannulas have been used in minimally invasive surgical procedures, such as laparoscopic and arthroscopic surgeries. Typically, in these procedures a small incision in made in the skin of a patient to access internal cavities, such as the abdomen or joints. A cannula is inserted into and is secured to the incision site. Surgical instruments are passed through the proximal openings of cannulas to enter a body cavity. During these procedures, the body cavity is inflated with an insufflated gas or liquid to create a surgical zone in the body cavity for surgical instruments. These cannulas generally have sealing members to seal the cannula to the incision site
U.S. patent application publication No. 2009/0275898 to Wenchell discloses a cannula with an internal inflatable membrane in its lumen. Insufflated gas enters the proximal end of the cannula to inflate the internal membrane to seal the lumen with or without a medical instrument therein. However, the pressure within the inflated membrane with the insufflated gas would be the same as the pressure within the body cavity with the insufflated gas, i.e., both would have the same pressure of the insufflated gas. This is less than ideal because there is no positive pressure gradient from the inflated internal membrane to the body cavity for a positive seal.
U.S. Pat. No. 9,161,747 to Whittaker et al discloses a cannula with a plurality of protrusions located on the cannula's outer surface. These protrusions are extended outward against the incision site when a collar or a cam is rotated or a telescoping sleeve is pulled relative to the cannula. These anchoring protrusions are rigid and are pressed against the incision site, which may cause post-procedure discomfort for the patient.
Hence, there remains a need for an improved surgical cannula that resolves these issues.